Process of preserving caustic materials



Patented Mar. 29, 1932 .UNETEB TATES WILLIAM R. JEAVONS, OF CLEVELAND HEIGHTS, AND MAHLON' J. RENTSCHLER, OF WILLOUG-HBY, OHIO PROCESS OF PRESERVING CAUSTIC MATERIALS No Drawing.

This invention has for its object to provide for the effective and convenient elimination from clay ware or ceramic products of scum such as is frequently noticeable on bricks employed in the building industry. The invention relates more particularly to the production of a composition of matter for the purpose'mentioned which is capable of being readily and conveniently incorporated into the clay from which such products are made, which can be handled withoutinjury, which can be shipped in ordinary paper contrainers, which can be stored without deterioration, and which can be manipulated by workmen of ordinary skill.

A common cause of scum formation on clay products is that many clays, as well as the water used in pugging or kneading the same, contain a percentage of soluble salts such as magnesium sulphate (MgSO calcium sulphate (CaSO potassium sulphate (K SO and sodium sulphate (Na SOQ which are deposited as scum on the surface of the molded mass on the evaporation of the solvent water. Often in the manufacture of clay products these salts will produce scum areas upon their surfaces through the simple drying out of the pug water used in kneading the clay. Variations in intensity and spread of the scum deposit may; occur by reason of slight variations in the compactness and porosity at scattered points throughout the molded clay mass as well as through variations in evaporating conditions at different portions of the clay-mass surface; at any rate, haphazard scum areas often appear on molded and formed projects upon the evaporation of the pugging or kneading water, causing much subsequent trouble and loss.

On products such as completely burned brick laid in walls, soluble salts contained in their mass will leach out under moist weather conditions and cause unsightly scum on the surfaces from which such leaching moisture evaporates.

Ofttimes detrimental or scumming salts in mortar or cement, used in laying brick walls, will on the weathering of such structures be dissolved and carried through or Application filed May 6, 1929. Serial No. 360,990.

over the bricks and be deposited as scum on their surfaces.

Heretofore, where a cure for 'scumming has been attempted, barium has been used almost universally in the form of barium carbonate, for the reason that it is the only barium compound that can be handled with any degree of satisfaction under the widespread conditions attending the initial kneading of raw clay, probably because it is a stable product and its efficiency, low though it may be, is unimpaired by'shipping and storage conditions. However, it is well known that its efficiency is exactly proportionate to its solubility, and as the solubility of pure precipitated barium carbonate is only about twenty-two parts ,per million of distilled water, its action is necessarily slow and the distribution of the powder for fragmental solution throughout the clay massisdiflicult and often imperfect.

The readily soluble barium salts which are neutral in reaction, such as barium chloride (B2101 barium fluoride (BaF barium nitrate (Ba(NO barium acetate etc., are not well adapted for scum-prevention, inasmuch as the scumming salt content of the clay varies considerably in different portions of the same clay bank and, unless the quantity of the barium salts is at all times kept in relatively correct proportion to the quantity of the salts in the clay, the result will be unsatisfactory, since with too little of these neutral barium salts there will be inefficiency and, if too much of these barium salts are employed, they will themselves form a detrimental scum on the product; furthermore the use of any of these soluble neutral barium salts results in the formation with the salts in the clay of secondary soluble salts, which of themselves cause scumming. Soluble compounds of barium which do not possess the disadvantages of the neutral soluble salts of barium above described are such basic soluble compounds of barium as barium monoxide (BaO) and barium hydrate (Ba(OH) which are considered ideal for scum prevention work, but which'are of such unstable character that their practical use in ceramic processes has heretofore been considered impossible.

Barium oxide is exceedingly hygroscopic, absorbing moisture instantly when exposed to the atmospherefland forming barium hy: drate whichflb ecausie of itsjtremendousatfin; ity for carbon dioxide, is immediately con- Verted into the relatively insoluble carbonate and thusloseskitsbasicmitality.

very caustic, producing severe burns it contacted with the skin; furthermore they-are inexperienced workmen.

Bari m onoxid wh h. i e p ll sirable for our purpose because it vis the most vital. 9f the soluble basic barium compounds 83, welllas because it -possessesseveral other 2Q aldy autages tobe pointed out hereinafter, is intensely hygroscopic. and 'e rcessively caustie; it dreuchcdjwith water,;it slacks with the evolution of ,such jntense heat as to. ignite. Wood or other, carbonaceous materials w th which it may be in. contact; and in consequeue: W n-il ar tate, itsmust be hitgpcd' w vy ir-tight teel drums ai; his" freight rates Ciyyst l z barium hyarl ie. is p op ly id is net mP-e lxs e d e h drate is of little :Yfl ue, as. by reason of .the mtense heat; eyolvied theconversion Will-beLlIitO a fused partiallyfleliydrated hard. insolubl am ssc f v v We have discoveredla novel manner oiipre sewing; ;the desirable properties; of soluble basiclbarium. compounds and have :thereby overcome the 'difliculties. enumerated to. the practicaLuse of theseioompounds and have made possible their shipment in paper bags at a low rate of freight to' the ceramic trade at. remote points, and in condition to be stored indefinitely and to be used-safely, economically I and, successfully for scum-prevention wOrki I y We accomplish these result-shy. .comminut ingz bone dry, finely fpowdered, colloidal, siliceous dust with dehydrated, finely powdered, 5Q s0luble bas,icbarium compound or compounds such as barium monoxide, barium hydrate, bariumsilicate, barium aluminate, etc. until a perfectly uniform mixture results. In practice,, we-prefer to use barium monoxide for the reason that it contains a higher percentage ofactive-barium than any other barium compound and i'snot attached-to any detrimental acid radical, and for the colloidal siliceous material we prefer to use highly refractory, clean, dry fireclay, but many natural and artificial materials, when properly, dried and ground, are also satisfactory for ourpurpose. The clay and the;soluble.barium compound, or compounds, are, weighed-off in such proper tions and ground together so thatthe finished difficult and troublesome to be handled by i covered orcoated very efiectually by clay so laclied bariumvmonoxidejj'bnt the monoX-i product will have uniformly disseminated therethrough approximately 20% of soluble barium. This proportion of ingredients has proven very satisfactory and eflicient in ceramic work for scum-prevention, but we do not limit ourselves to these exact proportions. lVhere the colloidal nature of the fireclay is to be preserved, it is extremely important that the same be not overheated in any portion. 7 Our experiments indicate that thepro- Barium monoxide and barium hydrate are:

tective'action of the fireclay is best realized when the latter is in a colloidal condition, as the individual particles of finely ground barium compound, or compounds, are thereby that on er posure of the mixture to airthe barium particles do not absorb moisture 501 carbonicacid gas. The alumina and silica contentsof the clay are important because they react ahigh temperature with-any excess. of barium compound, or compounds, which might be present in the clay above that necessary.. to react withthe soluble sulphatesinitiecIay. 1

, The incorporation ofthesoluble bariumoxide withaineutral clay or siliceous massis. accomplished (by apportioning the oxid'erand the massinamore or less roughbut perfectly dry state, ,then 'mixing and pulverizingthe mixture; this last step thoroughly .distributing the .oigide throughoutthe mass. v v

W hen barium hydrate is used as theflbarium base, the. dry hydrate crystals may be pulrized 'separately before mixing. withthe clay massif: desired; or they may be pulverizedjvith the mass in;the same .manneras whenbariuinoxideis used ,or the barium hydrate may be dissolved'in water and this Water ru'iX-edn'itli the clay or silicate mass which is subsequently pulverized after having been thoroughly dried. gr" unusual stability ofthe. bariuni content is desired, this result may be accomplished by heating. the mixture to a hi h degree in the process of its drying, thereby more intimately associating the barium withf the silicate-oftheclay. The loss ofcolioid'a'lity by this process is: compensated for by'the chemical reactionbetween the clay and the barium hydrate. Inasmuch as the different basic barium compounds that may be effective for the purposes 'ofl'our inventionhave greater or less reactivityfvalue in proportion to theirwe'ight or bulk as, for instance, barium oxide slac'ked to barium hydrate and containingthe waterof crystallization is of greater Weight or bulk than the oxide from which such hydrate is derivedcare should be taken ,to. cor, rectly apportion the carrier mass with refer once to the specific barium compound'employed for the production of a compositionof determinate strength relativeto its weight orrolume, as theobs'ervance of thisprecaui tion renders simple and accurate thefapportionment of the barium reactivity to theclay 3 masses employed for the manufacture of ceramic products by persons of ordinary skill.

In practice we prefer to use barium oxide as the barium base as in production the oxide is always perfectly dry, and its high activity is easily rendered more or less dormant by its dilution with the dry pulverized clay or silica; while barium hydrate is simply barium oxide hydrated, or slaked (i. e. plus water and minus heat) and takes more physical manipulation than the oxide to condition it for practical handling and usage.

The mixture of soluble basic barium compound, or compounds, with fireclay is not offensive to the sense of smell; the causticity of the barium compounds is shrouded and it is consequently not injurious to the hands or mucous membrances of workmen. The material consequently may be shipped in paper bags, thus taking a low rate of freight. When the material is mixed with water, the anhydrous barium compound slacks uniformly without any sensible or local heat formation. In this way the soluble barium compound spreads readily and rapidly throughout the clay mass in the pug mill, when used in the ceramic industry, reacting with the ,soluble sulphates and producing insoluble barium sulphate, thereby preventing the formation of scum without the production of any deleterious by-products.

This application is in some respects a continuation of our application No. 27 6,495, filed May 9,1928.

Having thus described our invention, what we claim is:

1. The process of preparing a soluble basic barium compound for shipment, storage, and use in the ceramic arts which consists in pulverizing the said compound, and permanently protecting the particles thereof by thoroughly and intimately mixing the same with a preponderance of finely pulverized anhydrous colloidal material.

2. The process of preparing a soluble basic barium compound for shipment, storage, and use in the ceramic arts which consists in mixing the said compound while in a finely pulverized condition with a preponderance of finely pulverized anhydrous colloidal material.

3. The process of preparing a soluble basic barium compound for shipment, storage, and use in the ceramic arts which consists in mixing the said compound while in a finely pulverized condition with a preponderance of finely divided anhydrous colloidal nonhygroscopic material.

4. A composition adapted for incorporation in the mass from which ceramic products are manufactured, the said composition comprising an intimate mixture of fresh finely pulverized soluble basic barium compound with a preponderance of finely divided anhydrous colloidal material.

5. A. composition adapted for incorporation in the mass from which ceramic products are manufactured, the said composition comprising a finely pulverized basic barium compound having the particles thereof protected by finely pulverized anhydrous colloidal material.

6. A composition adapted for incorporation in the mass from which ceramic products are manufactured, the said composition comprising a finely pulverized basic barium compound having the particles thereof separated and protected by finely pulverized anhydrous colloidal material.

In testimony whereof, we hereunto afiix our signatures.

WILLIAM R. JEAVONS. MAHLON J. RENTSCHLER. 

